[OpenTRV-dev] OpenTRV at local ham club

[Kevin Wood]

Hi Stuart,

You make a valid point. There's probably not much, if anything, there that
the Pi couldn't do itself.

Having said that, one of the other requirements is that it needs to be
fairly robust against power cuts, so the AVR started out as "supervising"
the Pi - providing battery backup power, commanding the Pi to shut down
cleanly when the power fails and so on, and it then seemed sensible to
make that also responsible for the other time-critical interfaces such as
driving the RFM and the dallas sensors. In fact, I have it in mind that,
if the Pi corrupts its' flash card and dies completely, the AVR will still
be able to control the heating.

Maybe I'm being too paranoid?

Kevin

> Kevin,
>
> Out of interest what's the reasoning behind having the AVR rather than
> getting the Pi to do it all directly ?
>
> Cheers
>
> Stuart
>
> On 29/07/14 10:35, Kevin Wood wrote:
>> Hi Bo,
>>
>> I'm actually working on something quite similar at the moment for a
>> second
>> home that needs frost protection / monitoring remotely, in this case
>> with
>> oil fired heating.
>>
>> My plan is a raspberry pi attached to an AVR which controls the heating
>> system.
>>
>> I'm thinking that the AVR can harvest temperature data from a couple of
>> OneWire sensors, run the heating and hot water schedules and control
>> relays that activate the heating system as required. It'll also have an
>> RFM on the board for later integration with OpenTRV and, if I can
>> reverse
>> engineer it, the wireless oil level sensor on the oil tank.
>>
>> R-Pi can host a web interface or, more likely in the first iteration,
>> provide a mechanism to at least SSH into it and check everything
>> remotely.
>> Of course it could also do email notifications and SMS would be possible
>> either via an internet SMS gateway, or just hang a GSM module off it
>> with
>> a cheap pay as you go SIM installed?
>>
>> Does this premises have internet connectivity?
>>
>> Kevin
>>
>>> I was at local ham club last night at looked at their heating
>>>
>>> So far i "THINK" its all electrical heating as there is no district
>>> heating
>>> installed, makes things a bit more easy since heat not used will go
>>> back
>>> to
>>> the cylinder :-D
>>>
>>>
>>> Next bit, there is one big room with 4 rads, which means one box should
>>> control them all, the box will be central placed. Its mainly old timers
>>> so
>>> the less complicated the better, the rest of the rooms are one rad per
>>> room.
>>>
>>>
>>> Mostly @kevin but others might chip in, they have some kind of remote
>>> control where they can send a text to turn stuff on and they would like
>>> to
>>> be able to turn on the heat remotely, how could we get to that?
>>>
>>> the point is that when the house is locked heating should turn off
>>> completely or run at 5degree to prevent frost issues. then either by
>>> remote
>>> command or when house is unlocked it should go to warm mode, there
>>> would
>>> be
>>> no need to sense if its day or night or if people are in the room etc.
>>> the
>>> alarm will output a signal when its on/off
>>>
>>> any ideas?
>>>
>>> /bo
>>>
>>> --
>>>
>>>                   |||||
>>>                 @(~Ô^Ô~)@
>>> -------------oOo---U---oOo-------------
>>> |                                     |
>>> |  Bo Herrmannsen                     |
>>> |                                     |
>>> |                                     |
>>> | "blessed are the "cracked",         |
>>> |  for its they who let in the light" |
>>> |                         Ooo         |
>>> |_________________ooO____(   )________|
>>>                   (   )    ) /
>>>                    \ (    (_/
>>>                     \_)
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